VAPOR REFRIGERANT CHARGING • Vapor can be added to the high- and low-pressure sides of the system while it is not operating • Vapor can be added to the low-pressure side of the system while it is operating • The refrigerant cylinder may need to be warmed in order to build up the pressure to properly charge the system. Jul 01, · And if one adds refrigerant, the air in the manifold tube needs to be dealt with, too. I highly recommend nicedatingusa.com (Update: site no longer available) for excellent info on refrigeration. He wrote a book, but much of the info is on the site, including how to effectively trouble shoot a Danfoss compressor (used in most of the boat refrigeration systems).
The compressor requires oil for lubrication of the moving parts in the compressor. In VERY large systems such as chillers, we are beginning to see oilless technologies with magnetic bearings like TurboCor refrigeratioon Danfoss shown abovehow to become a lay member of an employment tribunal these are still pretty rare in the field.
We are tasked with preventing liquid refrigerant from entering the compressor which can cause more rapid and potentially catastrophic oil loss. A flooded start is flooding that occurs during startup when liquid refrigerant was allowed to collect in the compressor, in the suction line or even in the evaporator. Both of these conditions can cause oil loss from the compressor as well as oil howw which can result in rapid compressor wear.
Preventing flooding rffrigeration a significant part of oil management and involves setting superheat properly and using other strategies such as crankcase heaters, non-bleed expansion valves and pump down on the off cycle to help keep liquid refrigerant out of refrigerahion compressor.
Another factor in lubrication is oil breakdown that can occur at high temperatures. Now, this does vary based on the compressor type, system and oil type, but is a generally accepted rule in the absence of hod more detailed guideline. On a properly functioning compressor, the mass flow rate amount of refrigerant moving through the compressor and the suction gas temperature are the primary factors that impact compressor discharge temperature.
Often high discharge temperatures occur when the suction pressure is low, superheat is low or compression ratio is high high head pressure, low suction pressure or some combination of these issues. Once the oil has left the compressor it must circulate through the system and return to the compressor crankcase and there are a few key factors that impact oil return.
The oil being utilized should be suited to the refrigerant type and of the proper ysstem for the compressor and the temperature application. Refrigerant velocity should be maintained according to how to choose a homeschool program recommendations and low velocity will primarily be an issue in evaporator coils and suction lines when the suction refrugeration is lower than design due to improper tubing sizing, low evaporator load, metering device underfeeding or undercharge.
On the other hand, too much oil can also lead to compressor issues and poor system performance. This often occurs when a new compressor is installed with a new oil charge on a system that previously had oil return issues. The new compressor will only add more oil to the circuit making the situation worse and again leading to a reoccurring failure. This is why diagnosing what is the best type of diet and finding WHY the old compressor failed is a huge part of the process so that you can make some oil adjustments if an oil return issue was found and rectified.
Miscibility — the ability of the oil to mix with and move with the refrigerant. Two units of measure are used with refrigeration oil.
In both cases a higher number is a thicker oil, just don't mix up refrigetation two standards. Hygroscopic — Many modern oils are hygroscopic which means they attract and hold moisture. It is very important to keep moisture away from hygroscopic oils to keep them from becoming contaminated. Hydrolysis — decomposition due to a reaction with water.
For example, POE oil decomposes into acids and alcohol in the presence of water which means that the once it decomposes it cannot be reconstituted with line driers or evacuation. Mineral — is a product of gasoline production. Naphthene based mineral oils are suitable for refrigeration systems using CFC or HCFC refrigerants and has been the standard oil used for hlw. It is compatible with mineral oil and compared to mineral oil, it has improved refrigerant miscibility at low-temperature conditions which is why it was and is often used with HCFC refrigerants in commercial refrigeration.
Polyalkylene Glycol PAG — a synthetic oil primarily used in automotive air conditioning systems. When oil does not return properly to the compressor it can cause compressor wear but it can also decrease system performance by coating the inside of the evaporator tubing walls and inhibiting heat transfer and can even cause restrictions. As always, read and follow manufacturers piping guidelines as the lower the velocity the more likely the oil is to have issues returning especially in retrofit applications where some Mineral or AB may still be present with the POE or PVE oils.
One good practice to use when running long runs of horizontal piping is to pitch it back towards the compressors. This is a common-sense practice no matter the oil, refrigerant or application whenever possible. This has been proven to be a myth, and to some extent manufacturers of retrofit, refrigerants have been suggesting adding small amounts of POE to mineral oil to help carry it through the system.
It is always better to move to POE or PVE oils from mineral when retrofitting to an HFC refrigerant but small amounts of mineral oil have proven to be rather inconsequential in most cases. One thing that has become clear with the advent of POE oil is the importance of proper brazing practices flowing nitrogenproper deep evacuation and keeping the oil away from air and moisture during storage. Keep the system clean and dry and use the correct oil in the correct amounts. Maintain proper oil return through proper pipe sizing, pitching and trapping as required and by maintaining appropriate deisgn velocity of the refrigerant.
Notify me of follow-up comments by email. Notify me of new posts by email. This site uses Akismet to reduce spam. Learn how your comment data is processed. By April 4, Share this Tech Tip: Facebook 0 Tweet 0. First a quick summary of the role of oil in the refrigerant circuit — The compressor requires oil for lubrication of the moving parts in the compressor.
First, let's cover the oil considerations a service tech can easily diagnose and impact. Technician Considerations We are tasked with preventing liquid refrigerant from entering the compressor which can cause more rapid and potentially catastrophic oil loss. Important Oil Terms Miscibility — the ability of the oil to mix with and move with the refrigerant. Oil Types Mineral — is a product of gasoline production.
Refrigeratin Piping for Oil Return When oil does not return properly to the compressor it can cause compressor wear but it can also decrease system performance by coating the inside of the evaporator tubing walls and inhibiting heat transfer and can even cause restrictions.
New Oil Considerations One thing that has become clear with the advent of POE oil is the importance of proper brazing practices flowing nitrogenproper deep evacuation and keeping the oil away from air and moisture during storage. Related Tech Tips. My grandpa called […]. A Christmas Meltdown There's a refrigeratiob to this story though it is a bit more of a cautionary tale than most I refdigeration.
You may find some common threads with both learning wisdom and remembering why throwing […]. What does "Saturated State" mean for What happens if usc beats notre dame Like we often do in these tech tips, we will start with the common how to add freon to a refrigeration system more practical explanation of saturation and then move to the more technical and nerdy explanation later.
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Connect the heating element to the proper voltage source to allow the refrigerant to heat and build up pressure. This pressure build-up will allow the pressure of the cylinder to be higher than that of the [refrigeration] system [being charged] and force the refrigerant into the system. • If a system is mothballed to suspend a deadline, maintain records documenting when the system was mothballed and when it was brought back on-line (i.e., when refrigerant was added back into the appliance). • Records to demonstrate a seasonal variance. • Reports on appliances that leak % or more of the full charge in a calendar year. Once the system is prepared and charged with refrigerant, be sure to choose the right type of sealant at your distributor. Sealants come in three varieties based on system size — less than tons; between and 5 tons; and more than 5 tons. The sealants come with a free charging hose, which should be used and discarded afterward.
Until suddenly you did. The can of refrigerant you have pictured is for auto air conditioners and while it is HFCa gas there is often an oil charge added to the can. Mixing these two oils is not a good idea and may cause a reaction if moisture has entered the system and will eat the metal evaporator from the inside out. Remember if you have had a leak and the system got below atmospheric then air and thus moisture will have been sucked into the closed system.
Large cold plate systems may require up to 24 hours of vacuuming. And if one adds refrigerant, the air in the manifold tube needs to be dealt with, too.
I highly recommend kollmann-marine. He wrote a book, but much of the info is on the site, including how to effectively trouble shoot a Danfoss compressor used in most of the boat refrigeration systems. Also an excellent read if you are making a new refrigeration system. He will also answer questions. Good luck finding the correct fitting to get the refrigerant from the can into your fridge.
Took us over a week to find and get that little valve for our nova cool and that was stateside! It actually might be easier in places like Mexico and the islands — we had no problems getting connectors in Mexico and refrigreant was sold many, many places.
Another good article Carolyn. When I saw the title in your Tips and Tricks email everyone should subscribe! You touched on them all. In-line fuses are a pet peeve of mine. Circuit protection is indeed an important thing. That is what circuit breakers and panel fuses are for. I see them often on radios and electronics poorly installed. Just because a device comes with an inline fuse holder does not mean it should be used.
If you power a number of devices from a single breaker, as often is appropriate for navigation electronics, use a sub-panel or commonly located fuses. Remember — circuit protection is not to protect the device — it is to protect distribution wiring from overheating.
Try this when the compressor is off — as you start turning the knob, the compressor should come on almost immediately. Another possibility is a blown fuse — or a bad breaker. Trace your wiring to see if there is an inline fuse, then check it if there is one.
You need to find the leak soapy water is the easiest way and then fix it. It is extremely easy to get too much refrigerant in the system, so that it is over-pressurized and not cooling. Whenever you make a change to the system, either adding or letting out refrigerant, give the system at least an day to settle in before you make another change. Find this helpful? Share and save: 50 Shares. Comments Hi Carolyn and Dave, The can of refrigerant you have pictured is for auto air conditioners and while it is HFCa gas there is often an oil charge added to the can.
Leave a Reply Cancel reply Your email address will not be published. Contact Contact Carolyn. What do you need help with? Share via. Facebook Messenger. Copy Link. Copy link. Copy Copied.
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